Typical end closures for beer and beverage containers have an opening panel and an attached leverage tab for pushing the opening panel into the container to open the end. The container is typically a drawn and ironed metal can, usually constructed from a thin plate of aluminum. End closures for such containers are also typically constructed from a cutedge of thin plate of aluminum or steel, formed into a blank end, and manufactured into a finished end by a process often referred to as end conversion. These ends are formed in the process of first forming a cutedge of thin metal, forming a blank end from the cutedge, and converting the blank into an end closure which may be seamed onto a container.
These types of container ends have been used for many years, with almost all such ends in use today being the “ecology” or “stay-on-tab” (“SOT”) ends in which the tab remains attached to the end after a tear panel, including large-opening ends (“LOE”), is opened. The tear panel being a portion of the can end defined by a frangible score length. The tear panel may be opened, that is the score may be severed, and the tear panel displaced at an angular orientation relative to the remaining portion of the can end, thus creating a pour opening through which the beverage may be poured from the container. The tear panel remains hingeably connected to the remaining portion of the can end by a hinge segment, leaving an opening through which the user draws the contents of the container. In an LOE, the pour opening is about 0.5 square inches in area.
Opening of the tear panel is operated by the tab which is attached to the can end by a rivet through a rivet island on the tab. The tab is typically attached to the can end such that a nose of the tab extends over a proximal portion of the tear panel in a stowage position. A lift end of the tab is located opposite the tab nose and provides access for a user to lift the lift end, such as with the user's finger, to force the nose against the proximal portion of the tear panel. With most can ends, the stowage position and opening position are in the same location; however, some can ends known in the art require rotation of the tab from a stowage position to the opening position prior to an opening sequence, i.e. the fracturing of the frangible score.
When the tab nose is forced against the tear panel, the score initially ruptures at a vent region of the score. This initial rupture of the score is primarily caused by the lifting force on the tab resulting in lifting of a central region of the can end, including the rivet and immediately adjacent the rivet. As the tab is lifted further, the score rupture propagates along the length of the score, eventually stopping at the hinge segment.
Venting is an initial release of pressure from within a pressurized container upon initial fracture of the score about the tear panel, typically upon the initial lifting of the lift end of the tab by a user.
One problem associated with these opening systems is pourability of the beverage from the container. Because these ends are not typically outfitted with a pressure equalization aperture, the beverage may “glug” as air enters the beverage container through the pour opening to replace the volume of the quickly exiting beverage emptied from the container. “Glug” refers to an uneven flow caused by the outside air attempting to enter the container through the pour opening. Thus, pressure equalization differs from venting in that venting is the initial release of pressure in a pressurized container, i.e. the “pop”, and pressure equalization is the act of replacing the volume of beverage with a volume of air.
Many years ago, prior to beverage containers having frangible tear panels of any sort, users opened beverage containers with church keys having a downturned sharpened beak used to pierce the end closure. The user would pierce the end closure twice creating a pour opening and an equalization opening. This method is often used today by beverage vendors at sporting stadiums and the like where speed of beverage delivery is important to serve many customers in short periods of time. Many efforts have been made to outfit SOT ends with some sort of equalization opening. None of these attempts have been universally adopted due in no small part to the significant drawbacks associated with each one.
For example, one method of improving pourability of SOT end closures involves enlarging the pour opening. However, the openings can rarely be made large enough to fully eliminate glugging. Additionally, when the openings are made very large, unwanted spillage becomes an issue from splashing, spewing, or spitting of the beverage through the very large pour opening. Moreover, the larger pour opening typically requires manual rotation of the tab about the rivet to apply tab nose forces in a plurality of locations on the closure to bend an enlarged tear panel into the container. Fully flexing a hinge region on the tab several times results in work hardening of the rivet island causing the metal to become brittle which could result in the tab undesirably breaking free from the closure. Also, the user must manually rotate the tab to a precise location without instruction in order for the tear panel to produce the larger pour opening.
Some designers have proposed providing a second tear panel in the end closure. These designs generally rely on use of an external puncturing tool, e.g. the church key, or using the SOT to open the second tear panel. Obviously requiring the user to supply an external puncturing tool is undesirable as it represents devolving of the art to the days of the church key. Using the SOT to open the second tear panel requires the manual rotating and flexing of the SOT described above which shares the drawbacks of the larger opening ends also described above. Finally, the size and location of these second tear panels are undesirable because the openings are too large resulting in spillage and/or too close to pour opening to create a sufficient pourability advantage.
One proposed method of eliminating manual rotation of the tab to open an equalization port requires providing a rocking tab or “teeter tauter” tab wherein one end of the tab is used to open the pour panel while the opposite end or some other portion of the tab is used to open the equalization port. However, rocking of the tab is undesirable because it could result in premature opening of one or both of the tear panels.
Efforts have placed such a vent feature close to or under the rivet island of the SOT and/or within a coined region surrounding the rivet. These features consist of a second frangible score that is fractured when the SOT is lifted to fracture the frangible score which partially defines the pour opening. These locations and methods are undesirable because they are located too close to the pour opening which could lead to unwanted spillage through the vent, and the method of severing does not provide the user with the option of using or not using the vent because the second score is automatically or naturally severed when the user fractures the main score partially defining the pour opening.
Another recent attempt at providing improved pour includes formation of a deboss channel at approximately a 1 o'clock position of the pour opening. There is some debate whether the deboss channel provides any improvement in pourability.
Thus, the problems associated with prior attempts to provide a pressure equalization port primarily center on the size and/or location of the port and/or method of opening. A non-exhaustive list of problems associated with these prior attempts includes the following singularly and in any combination: not providing the user an option of using/opening the port due to location, undesirably and/or unnecessarily too large, located too close to the dispensing opening, requires use of an enteral tool such as a church key, requires use of a user's finger to push down on the center panel in direct engagement therewith which could cause cuts on the user's finger due to sharp edges on the center panel, possible premature opening of the port, unacceptable/nonexistent pressure equalization within the container, and spills and splashes of the contents of the container. As is explained in greater detail below, the present invention reduces or eliminates these problems with container ends. The present invention provides variations for overcoming the specific difficulties associated with design, manufacture and use of large-open beverage container ends.
The present invention is provided to solve the problems discussed above and other problems, and to provide advantages and aspects not provided by prior end closures of this type. A full discussion of the features and advantages of the present invention is deferred to the following detailed description, which proceeds with reference to the accompanying drawings.